1. Field
The present disclosure relates to the use of thermostatic HVAC and other energy management controls that are connected to a computer network. More specifically, the disclosure relates to the use of remotely managed load switches incorporating thermostatic controllers to inform an energy management system, to provide enhanced efficiency, and to verify demand response with plug-in air conditioners and heaters.
2. Description of the Related Art
Refrigerant-based air conditioning has been on the market for nearly 100 years. Air conditioning systems may be thought of as belonging to one of three broad types: centralized systems, which locate the compressor and condenser outside the conditioned space, and use ductwork to move heat out of the conditioned space; window mount air conditioners, which are completely self-contained in a single enclosure, plug into an outlet, do not use ductwork, and are generally sized to cool a single room; and split systems, which are roughly halfway between the other two in design in that they are usually two-box systems, with the compressor outside the conditioned space, but mount the heat exchanger directly in an outside wall and thus also do not use ductwork.
Centralized systems tend to be most efficient in terms of cooling per unit of energy consumed, while window units tend to have the lowest mechanical efficiency, although there may be circumstances in which the effective cost of running a window unit to cool a single occupied room is lower than using a high-efficiency central air conditioner to cool the entire house when only the one room is occupied.
As energy prices rise, more attention is being paid to ways of reducing energy consumption. Because with most systems energy consumption is directly proportional to setpoint—that is, the further a given setpoint diverges from the balance point (the inside temperature assuming no HVAC activity) in a given house under given conditions, the higher energy consumption will be to maintain temperature at that setpoint), energy will be saved by virtually any strategy that over a given time frame lowers the average heating setpoint or raises the average cooling setpoint.
One of the most important ways to increase the operational efficiency of any heater or air conditioner is to make sure it is only used when and to the extent it is actually needed. Programmable thermostats have been available for decades for central heating and cooling systems. In theory, programmable thermostats can significantly reduce energy use with these systems. In practice, savings often prove harder to achieve, for a variety of reasons. Those shortcomings are overcome by innovations disclosed in patent application Ser. Nos. 12/183,990; 12/183,949; 12/211,733; and 12/211,690, the entirety of which are hereby incorporated herein by reference.
This system allows users to save significant energy with little or no loss of comfort. However, portable heaters and window air conditioners are not generally compatible with thermostats designed for central systems. Although some newer portable heaters and window air conditioners now include built-in thermostats, and future window air conditioners may have networking capabilities, there are millions of window air conditioners in the world that do not have such controls or communications capabilities.
Specialized load control thermostats designed to control window air conditioners and portable heaters are commercially available. They are designed to be plugged into a wall outlet, and to have the portable heater or window mount air conditioner plugged into them in turn using a switched outlet. These devices include a means for sensing temperature (such as a thermistor), means for choosing a desired thermal setpoint, and means for turning on and off the switched outlet. In the cooling context, for example, when the temperature as sensed by the internal sensor rises above the setpoint, the load controller powers the switched outlet, turning on the connected air conditioner. When the temperature as sensed by the internal sensor has fallen sufficiently, the load controller turns off power to the switched outlet, thereby switching off the air conditioner.
Also commercially available are non-networked load control switches that can be controlled via wireless communications. They are also designed to be plugged into an outlet, and to have an electrical device plugged into them in turn using a switched outlet. Such devices include means to communicate wirelessly with other components and for turning on and off the switched outlet.
Neither of these devices is likely to enable fully optimized energy management for a connected portable heater or window air conditioner. The challenge in using a conventional remote-controlled switch to manage the use of a window-mount air conditioner or space heater is that a critical data input required to optimize comfort and energy use is the temperature of the space being conditioned by the attached air conditioner or heater. This issue is at least partially addressed by adding a means for sensing temperature to the load control device, and thus in a sense converting the load control switch into a line-voltage thermostat. However, making the load control device into a self-contained thermostat requires significant additional complexity (and thus expense), such as a complete user interface, and is also likely to yield unsatisfactory results for several reasons. First, the location of the load control device is dictated by the location of the outlet into which the window-mount air conditioner must be connected. Whereas thermostats are normally situated in hallways or interior walls at roughly chest or shoulder level for an average adult, and well away from vents (which could cause the thermostat to shut off the HVAC system prematurely), the location of the electrical outlet nearest the air conditioner is likely to be very high or very low on an exterior wall. This location will both make programming difficult and distort the temperature readings obtained by the device, since the temperature in a given room is likely to vary by several degrees from floor to ceiling, and be unduly influenced by sunlight, nearby windows, etc., as well as by the attached heater or air conditioner itself.
These drawbacks are largely avoided by combining the thermostatic control capabilities of existing thermostatic load controllers with the communications capabilities of wireless communicating load controllers, and connecting the load control device via a network such as the Internet to a remote server that can manage the settings for the load control device and provide the ability to program settings from a variety of locations and using a variety of devices. This approach can also make it possible to omit most or all of the aspects of a user interface from the load control device itself, thereby reducing cost and complexity. This approach can also compensate for issues related to poor location of the load control device.
Although progress in residential HVAC control has been slow, tremendous technological change has come to the tools used for personal communication. When programmable thermostats were first offered, telephones were virtually all tethered by wires to a wall jack. But now a large percentage of the population carries at least one mobile device capable of sending and receiving voice or data or even video (or a combination thereof) from almost anywhere by means of a wireless network. These devices create the possibility that a consumer can, with an appropriate mobile device and a network-enabled heater or air conditioner, control his or her heater or air conditioner even when away from home. But systems that rely on active management decisions by consumers are likely to yield sub-optimal energy management outcomes—in part because consumers are unlikely to devote the attention and effort required to fully optimize energy use on a daily basis; in part because optimization requires information and insights that are well beyond all but the most sophisticated users.
Many new mobile devices now incorporate another significant new technology—the ability to geolocate the device (and thus, presumably, the user of the device). One method of locating such devices uses the Global Positioning System (GPS). The GPS system uses a constellation of orbiting satellites with very precise clocks to triangulate the position of a device anywhere on earth based upon arrival times of signals received from those satellites by the device. Another approach to geolocation triangulates using signals from multiple cell phone towers. Such systems can enable a variety of so-called “location based services” to users of enabled devices. These services are generally thought of as aids to commerce like pointing users to restaurants or gas stations, etc.
If the wall or window-mount air conditioner is plugged into a basic communicating load control device, it can be used to remotely turn off the air conditioner. This approach can be effective as a load management strategy from the perspective of a utility or other actor concerned with the health of the overall electric grid. Thus on hot summer afternoons, when air conditioning loads are highest, if the grid is threatened by a situation in which demand may exceed supply, a utility (or other party tasked with managing loads) may send a signal to switch off a large number of connected load controls, thereby reducing demand. Air conditioners represent a large percentage of such peak loads. The ability to address wall and window-mount air conditioners during such peak events could help to shed significant loads at critical times.
However, with existing solutions, this approach has serious drawbacks. Because there is no feedback loop between the load and the controller of the load, there is no way to take into account the conditions in the room or the preferences of the occupants or even to validate that the air conditioner has been shut off. Thus there is little incentive for the occupants of a given room to suffer significant personal discomfort in order to solve a grid-level problem. Indeed, the system arguably encourages consumers to find ways to defeat the external control. Such self-help could be as simple as removing the load controller from the circuit, or plugging the load (the air conditioner) into a different outlet. With a simple communicating load controller without a sophisticated feedback mechanism, there is no way for the remote manger to know whether such measures have been taken.
It would be advantageous for the load controller strategies for window and wall-mounted air conditioners (and in certain circumstances, space heaters) to take in to account the temperature conditions inside the space being cooled by the air conditioner attached to the load control device. It would also be advantageous for the load control strategies to take into account whether or not the room that is cooled by the air conditioner is occupied.
It would also be advantageous for load controller switches for window and wall-mounted air conditioners and plug-in heaters to include means for directly sensing occupancy of the conditioned space, and to communicate the occupancy status of the conditioned space to the remote server managing the operation of the attached window and wall-mounted air conditioners and plug-in heaters.
It would also be advantageous for load controller switches for window and wall-mounted air conditioners and plug-in heaters to include means for sensing and measuring current drawn by those attached devices, and to communicate the current drawn by said devices to the remote server managing the operation of the attached window and wall-mounted air conditioners and plug-in heaters.